The present invention relates to a thin film magnetic head and a method of manufacturing the thin film magnetic head, more precisely relates to a thin film magnetic head, in which a sub-magnetic pole layer is provided to a front end part of an upper magnetic pole layer, and a method of manufacturing the thin film magnetic head.
A partial sectional view of a writing section of a conventional thin film magnetic head is shown in FIG. 5. A symbol 10 stands for a lower magnetic pole layer; a symbol 12 stands for an electrically insulating layer; symbols 14a and 14b stand for coils; symbols 16a and 16b stand for electrically insulating layers; and a symbol 18 stands for an upper magnetic pole layer. A sub-magnetic pole layer 20 is faced to the lower magnetic pole layer 10 and connected to a front end part of the upper magnetic pole layer 18. The sub-magnetic pole layer 20 is extended forward from the front end part of the upper magnetic pole layer 18. A gap layer 22 is sandwiched between the sub-magnetic pole layer 20 and a front end part 10a of the lower magnetic pole layer 10.
A heaped layer 24 corresponds to a rear part of the sub-magnetic pole layer 20 and is formed between the sub-magnetic pole layer 20 and the lower magnetic pole layer 10. The heaped layer 24 is made of an electrically insulating material, e.g., SiO2 The heaped layer 24 is thicker than the gap layer 22, so that a step section is formed at a mid part of the sub-magnetic pole layer 20. Since the heaped layer 24 is thicker than the gap layer 22, a magnetic field can be concentrated between a front end face of the sub-magnetic pole layer 20 and a front end face of the lower magnetic pole layer 10, so that the writing section of the magnetic head is capable of efficiently writing data. Note that, the insulating layer, which constitutes the gap layer 22, covers the heaped layer 24, but the xe2x80x9cgap layer 22xe2x80x9d means a layer defining a gap between a front end of the lower magnetic pole layer 10 and that of the sub-magnetic pole layer 20.
Since the heaped layer 24 is formed between the lower magnetic pole layer 10 and the sub-magnetic pole layer 20, the rear part of the sub-magnetic pole layer 20 is separated from the lower magnetic pole layer 10. With this structure, no magnetic flux leaks from the rear part of the sub-magnetic pole layer 20 to the lower magnetic pole layer 10. Conventionally, the heaped layer 24 is formed by the steps of: forming an electrically insulating layer on the lower magnetic pole layer 10; and removing a part of the insulating layer, in which the gap layer 22 will be formed, by dry etching. In the dry etching step, the heaped layer 24 reacts, so the lower magnetic pole layer 10 is not removed, and etching time can be easily controlled.
However, in the conventional thin film magnetic head, a front end of the heaped layer 24, which is provided on the lower magnetic pole layer 10, rises with angle of xcex8 (Apex), e.g., about the right angle. Therefore, magnetic flux is apt to leak at the step-shaped portion of the sub-magnetic pole layer 20. The leakage of flux is caused by function of an edge of the step-shaped portion of the sub-magnetic pole layer 20. These days, very high recording density is required, but loss caused by the flux leakage is relatively great, so the flux leakage should be reduced so as to improve writing characteristics of the magnetic head.
Besides SiO2, resist is used as an electrically insulating material of the heaped layer 24. In the case of using resist, cracks are formed in the end face of the heaped layer 24 close to the lower magnetic pole layer 10 by thermal contraction while heat-curing the resist.
The present invention has been invented so as to solve the above described problems.
An object of the present invention is to provide a thin film magnetic head, in which angle of an end face of a heaped layer on a gap layer side with respect to a surface of a lower magnetic pole layer is made obtuse so as to prevent flux leakage at a rear part of the heaped layer and improve writing characteristics of the magnetic head.
Another object of the present invention is to provide a reliable thin film magnetic head, in which no cracks are formed in the heaped layer.
Other object of the present invention is to provide a method of manufacturing the thin film magnetic head of the present invention.
To achieve the objects, the present invention has following structures. The thin film magnetic head comprises: a lower magnetic pole layer; a gap layer provided on the lower magnetic pole layer; a sub-magnetic pole layer provided on the gap layer; an upper magnetic pole layer connected to a rear part of the sub-magnetic pole layer; and a heaped layer made of an electrically insulating material and provided on the rear side of the gap layer and between the lower magnetic pole layer and the sub-magnetic pole layer, the heaped layer having a slope portion, which is extended toward the gap layer and whose height is gradually reduced toward the same. With this structure, the gradual slope portion is formed in an end face of the heaped layer, so that flux leakage at the rear part of the sub-magnetic pole layer can be prevented, so that the writing characteristics of the magnetic head can be effectively improved. In the thin film magnetic head, the heaped layer having prescribed thickness and the gap layer may be integrated.
In the thin film magnetic head, a relationship between length of the gap layer (L1) and length of the slope portion (L2) may be L2 greater than L1.
The method of manufacturing a thin film magnetic head, which comprises a lower magnetic pole layer, a gap layer formed on the lower magnetic pole layer and an upper magnetic pole layer formed on the gap layer, comprises the steps of: forming an electrically insulating layer on the lower magnetic pole layer; covering a part of the insulating layer, which will be left as a heaped layer, with resist; diagonally irradiating ion-milling particles to the insulating layer; and forming the upper magnetic pole layer. With this method, the heaped layer can be easily formed by etching the insulating layer by ion milling. In the method a sub-magnetic pole layer may be formed on the gap layer after the ion-milling step.
In the method, an irradiating angle of the ion-milling particle may be adjusted so as to control a shape of a slope portion, which is extended from the heaped layer toward the gap layer and whose height is gradually reduced toward the same. Further, in the method, thickness of the resist may be adjusted so as to control the shape of the slope portion. With these methods, the shape of the slope portion can be easily controlled.